JP6915059B2 - Battery separator and lithium-ion battery and their manufacturing method - Google Patents

Description

Cross-references to related applications This disclosure gives priority to Chinese Patent Application Publication No. 201610753606.1, which was filed in China on August 29, 2016, the entire contents of which are incorporated herein by reference. Insist.

The present disclosure relates to the field of a lithium ion battery, and more particularly to a battery separator, a method for manufacturing the battery separator, a battery separator manufactured by the method, a lithium ion battery including the battery separator, and a method for manufacturing the lithium ion battery.

Polymer matrices that can swell liquid electrolytes and have lithium ion conduction properties include mainly polyethers (eg, polyethylene oxide (PEO)), polyacrylonitrile (PAN), and polyacrylates (eg, polymethyl methacrylate (eg, polymethyl methacrylate). PMMA) and its copolymers), polyvinylidene fluoride (polyvinylidene fluoride (PVDF) and vinylidene fluoride-hexafluoropropylene copolymer (P (VDF-HFP), etc.), among them, polyacrylates, etc. Is one of the more studied types of polymer matrices. These polymers structurally have functional groups similar to the carbonate solvent in the electrolyte, and thus have good compatibility with the electrolyte, metals. It has interfacial impedance with lithium electrode and good interfacial stability, which makes it an ideal polymer matrix.

The use of acrylate polymers as gel polymer electrolyte (GPE) matrices in lithium-ion batteries has been reported in many patent documents. The Chinese Patent Application Publication No. 1036333367A describes a self-crosslinked pure acrylic emulsion (main component) widely used in fields such as leather finishing, fiber treatment, plastic and metal corrosion protection, rust prevention, wooden fixtures, and exterior wall decoration. Is an acrylate polymer) is used for reference in the field of polymer lithium ion batteries, the use of numerous organic solvents is abandoned, and it is disclosed that environmentally friendly production of polymer lithium ion batteries is achieved. There is. When used in polymer lithium-ion batteries, this matrix has advantages such as high liquidity, high liquid retention, and good thermal stability. However, GPE has high bulk impedance and low ionic conductivity, so the resulting lithium-ion battery exhibits inadequate rate performance and large polarization during charging and discharging at high rates, and thus lithium-ion batteries. Performance is affected.

Pore formation can be performed to reduce the bulk impedance of the self-crosslinked GPE and increase the ionic conductivity. The phase inversion method is one of the main methods for producing a porous film, and mainly includes two forms of (1) solvent evaporation-precipitated phase separation and (2) immersion-precipitated phase separation. For example, Chinese Patent Application Publication No. 101062987A discloses a porous gel polymer electrolyte membrane and a method for producing the same. This porous gel polymer electrolyte membrane comprises 33-54% by weight of polyvinylidene fluoride, 3 to 15% by weight of acrylonitrile-polyethylene glycol monomethyl ether methacrylate copolymer, and 43 to 52% by weight of 1M lithium hexafluorophosphate carbonate electrolyte. including. The method for producing this porous gel polymer electrolyte membrane is as follows: first, a step of synthesizing a polyethylene glycol monomethyl ether methacrylate-acrylonitrile copolymer, and then a step of mixing a polyethylene glycol monomethyl ether methacrylate-acrylonitrile copolymer with polyvinylidene fluoride, and a mixture thereof. To prepare a polymer solution by dissolving in an N, N-dimethylacetamide solvent, a step of coating the polymer solution on a glass plate, and immersing the glass plate in deionized water to obtain a porous film. It comprises a step of adsorbing a lithium hexafluorophosphate carbonate electrolyte to obtain a porous gel polymer electrolyte membrane. Furthermore, the pore forming method used in this patent application is immersion-precipitation phase separation.

An object of the present disclosure is to overcome the inadequate rate defects of lithium-ion batteries due to high bulk impedance, low ionic conductivity, and large polarization in the case of high rate charging and discharging in self-bridged GPEs in existing technology. A novel battery separator, a method for manufacturing the battery separator, a battery separator manufactured by the method, a lithium ion battery including the battery separator, and a method for manufacturing the lithium ion battery are provided.

In particular, the present disclosure is a battery separator comprising a porous base film and a bonding layer adhered to the surface of at least one side of the porous base film, wherein the bonding layer is an acrylate crosslinked polymer and styrene-. Provided is a battery separator comprising an acrylate crosslinked copolymer and / or a vinylidene fluoride-hexafluoropropylene copolymer having a bonding layer with a porosity of 40-65%.

In the present disclosure, a slurry containing a self-crosslinked pure acrylic emulsion and a self-crosslinked styrene-acrylic emulsion and / or a vinylidene fluoride-hexafluoropropylene copolymer emulsion is adhered to the surface of at least one side of the porous base film. Further provided is a method of making a battery separator, comprising the step of allowing and then drying to form a bonding layer having a porosity of 40-65% on the surface of at least one side of the porous base film. do.

The present disclosure further provides a battery separator manufactured by the above method.

The present disclosure further provides a lithium ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a battery separator, wherein the battery separator is the battery separator described above.

Further, the present disclosure includes a step of sequentially laminating or winding a positive electrode plate, a battery separator, and a negative electrode plate to form a rod-shaped core, and then a step of injecting an electrolyte into the rod-shaped core and a step of sealing. The battery separator further provides a method for manufacturing a lithium ion battery, which is the battery separator.

In the battery separators provided by the present disclosure, self-crosslinked pure acrylic emulsions and self-crosslinked styrene-acrylic emulsions and / or foot are used to form a bonding layer having a specific porosity on a porous base film. A slurry containing a vinylidene-hexafluoropropylene copolymer emulsion is employed, and the bonding layer comprises an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer and / or a vinylidene fluoride-hexafluoropropylene copolymer. After absorbing the electrolyte, the junction layer has excellent lithium ion conductivity characteristics (GPE characteristics), significantly reduced bulk impedance, and significantly increased ion conductivity, and the battery separator containing the junction layer is a lithium ion battery. When used in, the rate charge-discharge performance is significantly improved, and the junction layer can suppress the decomposition of electrolytes in the battery at high temperatures, thereby improving high temperature cycle performance and high temperature storage performance. Can be done. Furthermore, in order not only to form an integrated battery rod core to increase the hardness of the pouch cell, but also to prevent the electrode plate from wrinkling during the battery cycle process, the bonding layer is a positive electrode plate and a negative electrode plate. Can be used as a transition layer to ensure that they are bonded together, thereby ensuring that the positive and negative electrodes, and the battery separator are in close contact at all times, reducing capacity loss and battery cycle performance. Can be improved and the practical life of the battery can be extended.

Other features and advantages of the present disclosure are described in detail in the detailed description below.

The drawings are included to provide a further understanding of the present disclosure, and the drawings form part of this specification. These are used to illustrate this disclosure with the following specific implementations, but are not intended to limit this disclosure.

6 is an SEM image at a magnification of 5000 times that of the porous self-crosslinked polymer film Sa1 obtained in the first embodiment. 6 is an SEM image at a magnification of 20000 times that of the porous self-crosslinked polymer film Sa4 on the CCL surface obtained in the fourth embodiment. 8 is an SEM image at a magnification of 20000 times that of the porous self-crosslinked polymer film Sa4 on the PE surface obtained in the fourth embodiment. It is a structural photograph (positive electrode and separator) of _{the SL435573 LiCoO 2} / graphite pouch type polymer lithium ion battery obtained in the first embodiment. It is a structural photograph (negative electrode and separator) of _{the SL435573 LiCoO 2} / graphite pouch type polymer lithium ion battery obtained in the first embodiment. 6 is a graph showing the relationship between the discharge capacity and the number of cycles of _{the SL435573 LiCoO 2} / graphite pouch-type polymer lithium-ion battery obtained in the first embodiment and the second comparative embodiment at 25 ° C. during the 1C cycle. 6 is a graph showing the relationship between the discharge capacity and the number of cycles of _{the SL435573 LiCoO 2} / graphite pouch-type polymer lithium-ion battery obtained in the first embodiment and the third embodiment at 45 ° C. during the 1C cycle.

Specific implementations of the present disclosure are described in detail below. It should be understood that the particular implementations described herein are used solely for illustration and description of the present disclosure and are not intended to be a limitation of the present disclosure.

It is understood that the endpoints and arbitrary values of the range disclosed herein are not limited to the exact range or value, and such range or value includes values close to those range or value. Should. For numeric ranges, the values between the endpoint values in different ranges, the endpoint values and individual point values in different ranges, and the values between the individual point values are combined together to create one or more new numeric ranges. These numerical ranges can be obtained and should be considered as expressly disclosed herein.

The battery separator provided by the present disclosure includes a porous base film and a bonding layer adhered to the surface of at least one side of the porous base film, in which the bonding layer is an acrylate crosslinked polymer and a styrene-acrylate crosslinked. It contains a copolymer and / or a vinylidene fluoride-hexafluoropropylene copolymer, and the porosity of the bonding layer is 40-65%.

"The bonding layer comprises an acrylate-crosslinked polymer and a styrene-acrylate-crosslinked copolymer, and / or a vinylidene fluoride-hexafluoropropylene copolymer" means that the bonding layer comprises an acrylate-crosslinked polymer and a styrene-acrylate-crosslinked copolymer, Vinylidene-hexafluoropropylene copolymer is not included, or acrylate crosslinked polymer and vinylidene fluoride-hexafluoropropylene copolymer are included, but styrene-acrylate crosslinked copolymer is not included, or acrylate crosslinked polymer, styrene-acrylate crosslinked copolymer, And vinylidene fluoride-hexafluoropropylene copolymer are meant to be included at the same time. Further, "including self-crosslinked pure acrylic emulsion and self-crosslinked styrene-acrylic emulsion, and / or vinylidene fluoride-hexafluoropropylene copolymer emulsion" can be similarly described.

The acrylate-crosslinked polymer means a polymer obtained by cross-linking polymerization of a reactive acrylate monomer. The degree of cross-linking of the acrylate-crosslinked polymer can be 2 to 30%, optionally 5 to 20%. In the present disclosure, the degree of cross-linking means the percentage value of the weight of the cross-linked polymer with respect to the total weight of the polymer. Further, the glass transition temperature of the acrylate crosslinked polymer is optionally −20 ° C. to 60 ° C., for example −12 ° C. to 54 ° C. According to the particular embodiment of the disclosure, the acrylate-crosslinked polymer is a mixture of a first acrylate-crosslinked polymer, a second acrylate-crosslinked polymer, and / or a third acrylate-crosslinked polymer, or a second acrylate-crosslinked polymer. Alternatively, it is a third acrylate crosslinked polymer, wherein the first acrylate crosslinked polymer is 70-80% by weight polymethylmethacrylate segment, 2-10% by weight ethylpolyacrylate segment, 10-20% by weight polyacrylic. The second acrylate crosslinked polymer comprises a butyl acid acid segment and a 2-10% by weight polyacrylic acid segment, the second acrylate crosslinked polymer is a 30-40% by weight polymethylmethacrylate segment, a 2-10% by weight ethyl polyacrylate segment, The third acrylate crosslinked polymer comprises 50-60% by weight of butyl polyacrylate segment and 2-10% by weight of polyacrylic acid segment, and the third acrylate crosslinked polymer is 50-80% by weight of methyl methacrylate segment, 2-10. The glass transition temperature of the first acrylate crosslinked polymer comprises 15-40% by weight butyl polyacrylate segment and 2-10% by weight polyacrylic acid segment by weight% ethyl polyacrylate segment, from 50 ° C. to It is 60 ° C., the glass transition temperature of the second acrylate-crosslinked polymer is −20 ° C. to −5 ° C., and the glass transition temperature of the third acrylate-crosslinked polymer is 30 ° C. to 50 ° C.

Styrene-acrylate crosslinked copolymer means a copolymer obtained by copolymerizing a styrene monomer and a reactive acrylate monomer. The weight ratio of styrene structural units to acrylate structural units in the styrene-acrylate crosslinked copolymer can be (0.5-2): 1, optionally (0.67-1.5): 1. The degree of cross-linking of the styrene-acrylate cross-linked copolymer can be 2 to 30%, optionally 5 to 20%. Further, the glass transition temperature of the styrene-acrylate crosslinked copolymer is optionally −30 ° C. to 50 ° C., for example −20 ° C. to 50 ° C. According to one of the embodiments of the present disclosure, the styrene-acrylate crosslinked copolymer is a 40-50% by weight polystyrene segment, 5-15% by weight polymethylmethacrylate segment, 2-10% by weight ethylpolyacrylate segment. , 30-40% by weight butyl polyacrylic acid segment, and 2-10% by weight polyacrylic acid segment, and the glass transition temperature of the styrene-acrylate crosslinked copolymer is 15 ° C. to 30 ° C.

The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is optionally −65 ° C. to −40 ° C., for example −60 ° C. to −40 ° C. According to one of the embodiments of the present disclosure, the vinylidene fluoride-hexafluoropropylene copolymer comprises 80-98% by weight of polyvinylidene fluoride segment and 2-20% by weight of polyhexafluoropropylene segment, optionally from 90 to 90% by weight. The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer containing 96% by weight of polyvinylidene fluoride segment and 4 to 10% by weight of polyhexafluoropropylene segment is −60 ° C. to −40 ° C.

According to one of the embodiments of the present disclosure, the bonding layer comprises an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer, but does not contain a vinylidene fluoride-hexafluoropropylene copolymer and is an acrylate crosslinked polymer vs. a styrene-acrylate crosslinked copolymer. The weight ratio is 1: (0.05-2), optionally 1: (1-2), or the bonding layer contains an acrylate crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer, but styrene-. The weight ratio of the acrylate-crosslinked polymer to vinylidene fluoride-hexafluoropropylene copolymer without the acrylate-crosslinked copolymer is 1: (0.3-25), optionally 1: (0.4-19), or The bonding layer contains an acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer, and the weight ratio of the acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer to the vinylidene fluoride to hexafluoropropylene copolymer is 1. : (0.01 to 2) :( 0.3 to 5), optionally 1: (0.05 to 1.5) :( 0.45 to 3). Through thorough research, the inventors of the present disclosure have shown that when the polymers are used in a combination of the above specific ratios, they significantly increase the liquid absorption and conductivity of the battery separator, as well as improve workability. I found it to be advantageous.

According to one of the embodiments of the present disclosure, the bonding layer comprises a first acrylate crosslinked polymer, a second acrylate crosslinked polymer, and a styrene-acrylate crosslinked copolymer, but not a vinylidene fluoride-hexafluoropropylene copolymer. , The weight ratio of the first acrylate crosslinked polymer to the second acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer is (5-10): 1: (10 to 13), or the bonding layer is the first. Includes acrylate-crosslinked polymer, second acrylate-crosslinked polymer, and vinylidene fluoride-hexafluoropropylene copolymer, but not styrene-acrylate-crosslinked copolymer, first acrylate-crosslinked polymer vs. second acrylate-crosslinked polymer vs. vinylidene fluoride The weight ratio of the-hexafluoropropylene copolymer is (5-15): 1: (5-12), or the bonding layer contains a second acrylate crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer. , The weight ratio of the second acrylate crosslinked polymer to vinylidene fluoride-hexafluoropropylene copolymer is 1: (5-20), or the bonding layer is the second acrylate, without the styrene-acrylate crosslinked copolymer. The weight ratio of the second acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer to the vinylidene fluoride to hexafluoropropylene copolymer comprises the crosslinked polymer, the styrene-acrylate crosslinked copolymer, and the vinylidene fluoride-hexafluoropropylene copolymer. 0.5-2): (1-5) or the bonding layer comprises a third acrylate crosslinked polymer, a styrene-acrylate crosslinked polymer, and a vinylidene fluoride-hexafluoropropylene copolymer, a third acrylate. The weight ratio of the crosslinked polymer to the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (0.5-2) :( 1-5), or the bonding layer is the first acrylate. Includes a crosslinked polymer, a second acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer, including a first acrylate crosslinked polymer vs. a second acrylate crosslinked polymer vs. a styrene-acrylate crosslinked copolymer vs. fluoride. Vinylidene-hexafluoropolymer The weight ratio of the ropylene copolymer is (10 to 15): 1: (0.5 to 2) :( 5 to 10).
The first acrylate crosslinked polymer comprises 70-80% by weight polymethylmethacrylate segment, 2-10% by weight ethylpolyacrylate segment, 10-20% by weight butylpolyacrylate segment, and 2-10% by weight. The second acrylate crosslinked polymer comprises 30-40% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, 50-60% by weight of butyl polyacrylate. The third acrylate crosslinked polymer comprises 50-80% by weight polymethyl methacrylate segment, 2-10% by weight ethyl polyacrylate segment, 15-5. Containing 40% by weight butyl polyacrylate segment and 2-10% by weight polyacrylic acid segment, the styrene-acrylate crosslinked copolymer comprises 40-50% by weight polystyrene segment, 5-15% by weight methyl polymethacrylate. The vinylidene fluoride-hexafluoropropylene polymer comprises segments, 2-10% by weight ethyl polyacrylate segment, 30-40% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment. , 80-98 wt% polyvinylidene fluoride segment and 2-20 wt% polyhexafluoropropylene segment, the glass transition temperature of the first acrylate crosslinked polymer is 50 ° C-60 ° C and the second acrylate. The glass transition temperature of the crosslinked polymer is -20 ° C to -5 ° C, the glass transition temperature of the third acrylate crosslinked polymer is 30 ° C to 50 ° C, and the glass transition temperature of the styrene-acrylate crosslinked copolymer is 15. The glass transition temperature of the vinylidene fluoride-hexafluoropropylene polymer is -60 ° C to -40 ° C.

According to the present disclosure, optionally, the bonding layer further comprises at least one of an acrylonitrile-acrylate copolymer, a chloroprene-acrylonitrile copolymer, and a styrene-butadiene copolymer. If the bonding layer further contains an acrylonitrile-acrylate copolymer, it is advantageous to increase the ionic conductivity of the battery separator inside the battery, and if the bonding layer further contains a chloroprene-acrylonitrile copolymer and / or a styrene-butadiene copolymer, it absorbs liquid. It is advantageous to reduce the liquid absorption rate of the battery separator so that the rate does not become too high, because if the liquid absorption rate is too high, the positive electrode and the negative electrode inside the battery lack electrolyte and the battery performance deteriorates. Because.

If the bonding layer further comprises an acrylonitrile-acrylate copolymer, the weight ratio of the acrylonitrile-acrylate copolymer to the acrylate-crosslinked polymer is optionally (0.05-2): 1, for example (0.08-1.85): 1. be. If the bonding layer further comprises a chloroprene-acrylonitrile copolymer, the weight ratio of the chloroprene-acrylonitrile copolymer to the acrylate crosslinked polymer is optionally (0.15-7): 1, for example (0.2-6): 1. If the bonding layer further comprises a styrene-butadiene copolymer, the weight ratio of the styrene-butadiene copolymer to the acrylate-crosslinked polymer is optionally (0.05-2): 1, for example (0.08-1.85): 1. be.

According to the battery separator provided by the present disclosure, the surface density of the one side of the bonding layer optionally 0.05~0.9mg / cm ^2, for example 0.1~0.6mg / cm ^2.

According to the battery separator provided by the present disclosure, the thickness of one side of the bonding layer is optionally 0.1 to 1 μm, for example 0.2 to 0.6 μm.

The type of porous base membrane is not particularly limited to the present disclosure and may be a conventional option in the art, eg, a polymer base membrane or a ceramic base membrane, where the ceramic base membrane is: It is the same as a conventional ceramic base film in the art and includes a polymer base film and a ceramic layer disposed on the surface of at least one side of the polymer base film. The polymer-based membrane can be an existing polyolefin membrane. Examples of the polyolefin film include a polypropylene (PP) film, a polyethylene (PE) film, and a PE / PP / PE three-layer film. The ceramic layer generally contains ceramic particles and a binder, and the content of the binder can be 1 to 10% by weight, optionally 3 to 7% by weight, based on 100 parts by weight of the ceramic particles. Ceramic particles are generally from at least one of Al ₂ O ₃ , SiO ₂ , SnO ₂ , ZrO ₂ , TiO ₂ , SiC, Si ₃ N ₄ , CaO, MgO, ZnO, BaTIO ₃ , LiAlO ₂ , and BaSO _4. Be selected. The binder can generally be at least one of polyacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polyacrylonitrile, polyvinylpyrrolidone, polyimide, polyvinyl alcohol and the like, optionally polyacrylate, eg-. It can be a polyacrylate having a glass transition temperature of 40 ° C to 0 ° C. Polyacrylates having a glass transition temperature of −40 ° C. to 0 ° C. can be copolymers of monomer units such as butyl acrylate, ethyl acrylate, methyl methacrylate, acrylic acid, and the like. When a polyacrylate having a glass transition temperature of -40 ° C to 0 ° C is used as a binder, the processability can be improved without affecting the bonding strength and gas permeability of the ceramic base membrane, and it is used for industrial purposes. The possibilities open up. Further, the thickness of the ceramic layer on one side can be 0.1 to 3 μm, optionally 0.5 to 2 μm.

According to the battery separator provided by the present disclosure, the overall thickness of the porous base membrane can be generally 9-22 μm, optionally 9-11 μm.

The method for producing a battery separator provided by the present disclosure is to make a slurry containing a self-crosslinked pure acrylic emulsion, a self-crosslinked styrene-acrylic emulsion, and / or a vinylidene fluoride-hexafluoropropylene copolymer emulsion at least one of a porous base film. Includes a step of adhering to the surface on one side and then drying to form a bonding layer having a porosity of 40-65% on the surface of at least one side of the porous base film.

The self-crosslinked pure acrylic emulsion means an emulsion obtained by emulsion polymerization of a reactive acrylate monomer. The degree of cross-linking of the acrylate-crosslinked polymer in the self-crosslinked pure acrylic emulsion can be 2-30%, optionally 5-20%. Further, the glass transition temperature of the acrylate-crosslinked polymer in the self-crosslinked pure acrylic emulsion is optionally −20 ° C. to 60 ° C., for example −12 ° C. to 54 ° C. According to one of the embodiments of the present disclosure, the self-crosslinking pure acrylic emulsion is a mixture of a first self-crosslinking pure acrylic emulsion, a second self-crosslinking pure acrylic emulsion, and / or a third self-crosslinking pure acrylic emulsion. , Or a second self-crosslinked pure acrylic emulsion, or a third self-crosslinked pure acrylic emulsion, wherein the acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion is a 70-80% by weight polymethylmethacrylate segment. 2-10% by weight ethyl polyacrylate segment, 10 to 20% by weight butyl polyacrylate segment, and 2 to 10% by weight polyacrylic acid segment, acrylate cross-linked in second self-crosslinked pure acrylic emulsion The polymer was 30-40% by weight methyl methacrylate segment, 2-10% by weight ethyl polyacrylate segment, 50-60% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment. The acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion contains 50-80% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, and 15-40% by weight of poly. The glass transition temperature of the acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion, which comprises a butyl acrylate segment and 2-10% by weight polyacrylic acid segment, is 50 ° C-60 ° C and a second self. The glass transition temperature of the acrylate crosslinked polymer in the crosslinked pure acrylic emulsion is -20 ° C to -5 ° C, and the glass transition temperature of the acrylate crosslinked polymer in the third self-crosslinked pure acrylic emulsion is 30 ° C to 50 ° C. Is.

The self-crosslinked styrene-acrylic emulsion means an emulsion obtained by copolymerizing a styrene monomer and a reactive acrylate monomer. Here, the weight ratio of the styrene structural unit to the acrylate structural unit in the styrene-acrylate copolymer can be (0.5 to 2): 1, optionally (0.67 to 1.5): 1. The degree of cross-linking of the styrene-acrylate cross-linked copolymer in the self-cross-linked styrene-acrylic emulsion can be 2 to 30%, optionally 5 to 20%. Further, the glass transition temperature of the styrene-acrylate crosslinked copolymer in the self-crosslinked styrene-acrylic emulsion is optionally −30 ° C. to 50 ° C., for example −20 ° C. to 50 ° C. According to one of the embodiments of the present disclosure, the styrene-acrylate crosslinked copolymer in the self-crosslinked styrene-acrylic emulsion is a 40-50% by weight polystyrene segment, 5-15% by weight polymethylmethacrylate segment, 2-10. The glass transition temperature of the styrene-acrylate crosslinked copolymer contains 15% by weight of ethyl polyacrylate segment, 30 to 40% by weight of butyl polyacrylate segment, and 2 to 10% by weight of polyacrylic acid segment, and the glass transition temperature is 15 ° C. to 30 ° C. ℃.

The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer in the vinylidene fluoride-hexafluoropropylene copolymer emulsion is optionally −65 ° C. to −40 ° C., for example −60 ° C. to −40 ° C. According to one of the embodiments of the present disclosure, the vinylidene fluoride-hexafluoropropylene copolymer in the vinylidene fluoride-hexafluoropropylene copolymer emulsion contains 80-98% by weight of polyvinylidene fluoride segments and 2 to 20% by weight of poly. The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer, which comprises a hexafluoropropylene segment and optionally contains 90-96% by weight of polyvinylidene fluoride segment and 4-10% by weight of polyvinylidene fluoride segment, is optional. It is -60 ° C to -40 ° C.

Vinylidene fluoride-hexafluoropropylene copolymer emulsions are commercially available or can be obtained by a variety of existing methods, or obtained by preparing emulsions from vinylidene fluoride-hexafluoropropylene copolymer powders. be able to. According to one particular embodiment of the disclosure, vinylidene fluoride-hexafluoropropylene copolymer emulsions are:
(1) A step of dissolving the dispersant in water and selectively adjusting the pH value to obtain an aqueous solution A of the dispersant.
(2) The vinylidene fluoride-hexafluoropropylene copolymer powder is slowly added to the aqueous solution A of the dispersant under stirring, and after the addition of the vinylidene fluoride-hexafluoropropylene copolymer powder is completed, the mixture is stirred at low speed and then at high speed. And finally prepared by the process of uniformly dispersing the mixture under high pressure to form a vinylidene fluoride-hexafluoropropylene copolymer emulsion.

The dispersant is a water-soluble polymer dispersant, and examples thereof include an ionic type (polymer electrolyte) and a non-ionic type. Here, the ionic dispersant is neutralized with a base for alcohol esterification following homopolymerization of a carboxyl-containing vinyl monomer (eg, acrylic acid, maleic anhydride, etc.) or copolymerization with another monomer. It is a polycarboxylic acid dispersant obtained by the above. Examples of ionic dispersants include polyacrylic acid (PAA), polyethyleneimine (PEI), cetyltrimethylammonium bromide (CTAB), polyamide, polyacrylamide (PAM), acrylic-acrylate copolymer, acrylic-acrylamide copolymer [P]. (AA / AM)], ammonium acrylate-acrylate copolymer, styrene-maleic anhydride copolymer (SMA), styrene-acrylic copolymer, acrylic-maleic anhydride copolymer, maleic anhydride-acrylamide copolymer and the like. It is not limited. Examples of the nonionic dispersant include polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), fatty alcohol polyoxyethylene ether (JFC) and the like. The weight average molecular weight of the dispersant is 100 to 500,000 g / mol, optionally 1000 to 100,000 g / mol. The concentration of the aqueous solution A of the dispersant is 0.01 to 10% by weight, optionally 0.05 to 5% by weight, for example 0.1 to 2% by weight. Based on the amount of vinylidene fluoride-hexafluoropropylene copolymer powder, the dispersant is used in an amount of 0.05 to 10% by weight, optionally 0.1 to 6% by weight, for example 0.1 to 2% by weight. NS. If the ionic dispersant used is an anionic polymer (eg, PAM), the solution is adjusted to pH = 8-9, whereby the anionic polymer is completely dissociated, thereby vinylidene fluoride-. Hexafluoropropylene copolymer powder is effectively protected, allowing stable dispersion of vinylidene fluoride-hexafluoropropylene copolymer powder in the aqueous phase. If the ionic dispersant used is a cationic polymer (eg, PEI, CTAB), the solution is adjusted to pH = 4-5, whereby the cationic polymer is sufficiently dissociated, thereby fluorination. The vinylidene-hexafluoropropylene copolymer powder is effectively protected, allowing stable dispersion of the vinylidene fluoride-hexafluoropropylene copolymer powder in the aqueous phase. If the dispersant used is a nonionic polymer dispersant, the pH value of the solution will not be adjusted.

According to one of the embodiments of the present disclosure, the slurry comprises a self-crosslinked pure acrylic emulsion and a self-crosslinked styrene-acrylic emulsion, but does not contain a vinylidene fluoride-hexafluoropropylene copolymer emulsion and is self-crosslinked pure acrylic emulsion vs. self. The weight ratio of the solid content of the crosslinked styrene-acrylic emulsion is 1: (0.05-2), optionally 1: (1-2), or the slurry is a self-crosslinked pure acrylic emulsion and vinylidene fluoride. The weight ratio of the solid content of the self-crosslinked pure acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion is 1: (0.3), including the -hexafluoropropylene copolymer emulsion but not the self-crosslinked styrene-acrylic emulsion. ~ 25), optionally 1: (0.4-19), or the slurry comprises a self-crosslinked pure acrylic emulsion, a self-crosslinked styrene-acrylic emulsion, and a vinylidene fluoride-hexafluoropropylene copolymer emulsion and self. The weight ratio of the solid content of the crosslinked pure acrylic emulsion to the self-crosslinked styrene-acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion was 1: (0-80.05-2) :( 0.30-5). It is optionally 1: (0.05 to 1.5) :( 0.45 to 3). Through thorough research, the inventors of the present disclosure have shown that when the emulsions are used in a combination of the above specific ratios, the liquid absorption and conductivity of the ceramic separator are increased, and the workability is improved. I found it to be advantageous.

According to one of the embodiments of the present disclosure, the slurry comprises a first self-crosslinked pure acrylic emulsion, a second self-crosslinked pure acrylic emulsion, and a self-crosslinked styrene-acrylic emulsion, but with vinylidene fluoride-hexafluoropropylene. The weight ratio of the solid content of the first self-crosslinked pure acrylic emulsion to the second self-crosslinked pure acrylic emulsion to the self-crosslinked styrene-acrylic emulsion, which does not contain the copolymer emulsion, is (5-10): 1: (10 to 10). 13) or the slurry contains a first self-crosslinked pure acrylic emulsion, a second self-crosslinked pure acrylic emulsion, and a vinylidene fluoride-hexafluoropropylene copolymer emulsion, but includes a self-crosslinked styrene-acrylic emulsion. The weight ratio of the solid content of the first self-crosslinked pure acrylic emulsion to the second self-crosslinked pure acrylic emulsion to vinylidene fluoride-hexafluoropropylene copolymer emulsion is (5 to 15): 1: (5 to 12). ) Or the slurry contains a second self-crosslinked pure acrylic emulsion and a vinylidene fluoride-hexafluoropropylene copolymer emulsion, but does not contain a self-crosslinked styrene-acrylic emulsion and is paired with a second self-crosslinked pure acrylic emulsion. The weight ratio of the solid content of the vinylidene fluoride-hexafluoropropylene copolymer emulsion is 1: (5-20), or the slurry is a second self-crosslinked pure acrylic emulsion, self-crosslinked styrene-acrylic emulsion, and The weight ratio of the solid content of the second self-crosslinked pure acrylic emulsion to the self-crosslinked styrene-acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion containing the vinylidene fluoride-hexafluoropropylene copolymer emulsion is 1: (0). .5-2): (1-5) or the slurry comprises a third self-crosslinked pure acrylic emulsion, a self-crosslinked styrene-acrylic emulsion, and a vinylidene fluoride-hexafluoropropylene copolymer emulsion, a third. Is the weight ratio of the solid content of the self-crosslinked pure acrylic emulsion to the self-crosslinked styrene-acrylic emulsion to vinylidene fluoride-hexafluoropropylene copolymer emulsion 1: (0.5-2) :( 1-5)? , Or the slurry is the first self-crosslinked pure acrylic Includes emulsion, second self-crosslinked pure acrylic emulsion, self-crosslinked styrene-acrylic emulsion, and vinylidene fluoride-hexafluoropropylene copolymer emulsion, first self-crosslinked pure acrylic emulsion vs. second self-crosslinked pure acrylic emulsion vs. self. The weight ratio of the solid content of the crosslinked styrene-acrylic emulsion to vinylidene fluoride-hexafluoropropylene copolymer emulsion is (10 to 15): 1: (0.5 to 2) :( 5 to 10).
The acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion contains 70-80% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, and 10-20% by weight of butylpolyacrylate segment. , And 2-10% by weight polyacrylic acid segments, and the acrylate-crosslinked polymer in the second self-crosslinked pure acrylic emulsion is 30-40% by weight polymethyl methacrylate segment, 2-10% by weight polyacrylic. The acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion containing an ethyl acid acid segment, 50-60% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment was 50-80% by weight. Polymethylmethacrylate segment, 2-10% by weight ethylpolyacrylate segment, 15-40% by weight butylpolyacrylate segment, and 2-10% by weight polyacrylic acid segment, self-crosslinked styrene-acrylic The styrene-acrylate crosslinked copolymer in the emulsion is 40-50% by weight polystyrene segment, 5-15% by weight polymethyl methacrylate segment, 2-10% by weight ethyl polyacrylate segment, 30-40% by weight poly. The vinylidene fluoride-hexafluoropropylene copolymer comprising a butyl acrylate segment and 2-10% by weight polyacrylic acid segment and in a vinylidene fluoride-hexafluoropropylene copolymer emulsion is 80-98% by weight of vinylidene fluoride. The glass transition temperature of the acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion, including the segments and 2-20% by weight polyhexafluoropropylene segments, is 50 ° C-60 ° C and the second self-crosslinked pure acrylic. The glass transition temperature of the acrylate-crosslinked polymer in the emulsion is −20 ° C. to −5 ° C., the glass transition temperature of the acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion is 30 ° C. to 50 ° C., and styrene. The glass transition temperature of the −acrylate crosslinked copolymer is 15 ° C to 30 ° C, and the glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is −60 ° C to −40 ° C.

According to the present disclosure, optionally, the slurry further comprises at least one of an acrylonitrile-acrylate copolymer emulsion, a chloroprene-acrylonitrile emulsion, and a styrene-butadiene latex, and if the slurry further comprises an acrylonitrile-acrylate copolymer emulsion, inside the battery. It is advantageous for increasing the ionic conductivity of the battery separator, and if the slurry further contains a chloroprene-acrylonitrile emulsion and / or a styrene-butadiene latex, it reduces the liquid absorption of the battery separator so that the liquid absorption does not become too high. This is advantageous because if the liquid absorption rate is too high, the positive and negative electrodes inside the battery will be deficient in electrolyte and the battery performance will be reduced.

If the slurry further comprises an acrylonitrile-acrylate copolymer emulsion, the weight ratio of the solid content of the acrylonitrile-acrylate copolymer emulsion to the solid content of the self-crosslinked pure acrylic emulsion is optionally (0.05-2): 1, eg, ( 0.08 to 1.85): 1. If the slurry further comprises a chloroprene-acrylonitrile emulsion, the weight ratio of the solid content of the chloroprene-acrylonitrile emulsion to the solid content of the self-crosslinked pure acrylic emulsion is (0.15-7): 1, for example (0.2 to). 6): 1. If the slurry further contains styrene-butadiene latex, the weight ratio of the solid content of the styrene-butadiene latex to the solid content of the self-crosslinked pure acrylic emulsion is (0.05-2): 1, for example (0.08-. 1.85): 1.

Further, in order to promote adhesion of the slurry to the porous base membrane, optionally, the total solid content of the slurry is 0.5-25% by weight, for example 1-20% by weight, for example 1-10% by weight. be.

As the mounting method, a spraying method and / or a screen printing method can be arbitrarily adopted. Porous (discontinuous) self-crosslinked polymer coating without the need for a phase separation process by forming a non-uniform coating by spraying and / or screen printing to directly form the porous film with porosity. Can be formed.

The spraying and screen printing conditions of the present disclosure are not particularly limited. For example, the spray temperature is optionally 30 ° C to 80 ° C, for example 40 ° C to 75 ° C. The screen printing temperature is optionally 30 ° C to 80 ° C, for example 40 ° C to 75 ° C.

The amount of slurry is arbitrary so that the thickness of one side of the bonded layer to be formed is 0.1 to 1 μm, for example 0.2 to 0.6 μm.

The drying temperature of the slurry of the present disclosure is not particularly limited, and is optionally 30 ° C. to 80 ° C., for example, 40 ° C. to 75 ° C.

The types and thicknesses of the porous base membranes have been described above and are not described herein below.

The present disclosure further provides a battery separator manufactured by the above method.

Further, the present disclosure includes a positive electrode plate, a negative electrode plate, an electrolyte, and a battery separator, and the battery separator further provides a lithium ion battery which is the battery separator.

Electrolytes are well known to those of skill in the art and typically consist of an electrolyte lithium salt and an organic solvent. Here, the electrolyte lithium salt is a dissociable lithium salt, and is selected from the group consisting of _{, for example, lithium hexafluorophosphate (LiPF 6} ), lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF _{4), and the like.} The organic solvent may be at least one, such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), vinylene carbonate (VC) and the like. It can be at least one selected from the group consisting of. Optionally, the concentration of the electrolyte lithium salt in the electrolyte is 0.8-1.5 mol / L.

The positive electrode plate is made by coating a slurry prepared from a positive electrode material for a lithium ion battery, a conductive substance, and a binder on an aluminum foil. The positive electrode material used is any positive electrode material that can be used for lithium ion batteries, such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium iron phosphate. At least one such as (LiFePO ₄ ) can be mentioned.

The negative electrode plate is made by coating a copper foil with a slurry prepared from a negative electrode material for a lithium ion battery, a conductive substance, and a binder. The negative electrode material used includes any negative electrode material that can be used for lithium ion batteries, such as at least one such as graphite, soft carbon, hard carbon and the like.

A major improvement in the lithium-ion batteries provided by the present disclosure is that new ceramic separators are used and the placement (connection method) of the positive electrode plate, negative electrode plate, battery separator, and electrolyte can be the same as the existing technology. Is. This is well known to those of skill in the art and is not described herein below.

The lithium-ion batteries provided by the present disclosure have the advantages of high hardness, good cycle performance, long working life, good rate charge-discharge performance, and good high temperature performance.

The method for manufacturing a lithium ion battery provided by the present disclosure includes a step of sequentially stacking or winding a positive electrode plate, a battery separator, and a negative electrode plate to form a rod-shaped core, and then a step of injecting an electrolyte into the rod-shaped core. The battery separator includes the sealing step and is the battery separator described above.

Here, the materials or compositions of the positive electrode plate, the negative electrode plate, and the electrolyte are described above and are not described below in the present specification.

The present disclosure will be described in detail below, depending on the embodiment.

In the following embodiments and comparative embodiments, the physicochemical parameters of the raw materials are:
(1) Composition of self-crosslinked pure acrylic emulsion:
1.1) 1040: 15% by weight butyl polyacrylate segment, 75% by weight methyl methacrylate segment, 5% by weight ethyl polyacrylate segment, and 5% by weight polyacrylic acid segment, glass transition temperature Tg = 54 ° C., solid content is 50% by weight, Shanghai Aigao Chemical Co., Inc. , Ltd. ,
1.2) 1005: 55% by weight butyl polyacrylate segment, 35% by weight polymethyl methacrylate segment, 5% by weight ethyl polyacrylate segment, and 5% by weight polyacrylic acid segment, glass transition temperature Tg = -12 ° C., solid content is 50% by weight, Shanghai Aigao Chemical Co., Inc. , Ltd. , And 1.3) 1020: 25% by weight butyl polyacrylate segment, 65% by weight methyl methacrylate segment, 5% by weight ethyl polyacrylate segment, and 5% by weight polyacrylic acid segment, glass transition. The temperature Tg = 40 ° C. and the solid content is 50% by weight. , Ltd. ..
(2) Composition of self-crosslinked styrene-acrylic emulsion:
S601: 45% by weight polystyrene segment, 35% by weight butyl polyacrylate segment, 10% by weight polymethyl methacrylate segment, 5% by weight ethyl polyacrylate segment, and 5% by weight polyacrylic acid segment, glass. The transition temperature Tg = 22 ° C. and the solid content is 50% by weight. , Ltd. ..
(3) Vinylidene Fluoride-Hexafluoropropylene Copolymer Emulsion:
10278: 95% by weight polyvinylidene fluoride segment and 5% by weight polyhexafluoropropylene segment, weight average molecular weight Mw = 450,000, glass transition temperature -55 ° C., solid content 30% by weight, Arkema.
(4) Vinylidene Fluoride-Hexafluoropropylene Copolymer Powder:
Kynar powerflex LBG: The composition is the same as 10278, the difference being that it has been dried and purified, Arkema.

In the following embodiments and comparative embodiments, the surface density of the bonding layer was measured by the following method: a 0.2m × 0.2m PTFE plate and a PTFE plate containing the bonding layer were used, respectively, and M ₀ ( When the weights of g) and M (g) are weighed, the surface density = [(MM ₀ ) /0.04] g / m ² .

Embodiment 1
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1005), and self-crosslinked styrene-acrylic emulsion (Shanghai). Aigao Chemical Co., Ltd. (named S601) was mixed at a mass ratio of 9: 1:10 solid content, an appropriate amount of water was added thereto, and the mixture was uniformly stirred to make 1% by weight of the total solid. A slurry having a content was prepared.

(2) The above slurry was purchased from CCL / PE / CCL (1 μm / 9 μm / 1 μm, where the PE layer was purchased from SK Corporation in Japan, the name of which was BD1201, and the CCL layer was 95% by weight of alumina. On the surface on both sides of the base film (and so on) composed of ceramic particles and 5% by weight polyacrylate with a glass transition temperature of -20 ° C and on the surface on one side of the PTFE plate (and so on). By spraying (at a spray temperature of 40 ° C.) and then drying at 50 ° C., a CCL / PE / CCL base film (called a battery separator Sa1) containing a porous self-crosslinked polymer film (bonding layer, the same applies hereinafter) Sa1 is used. ), And the porous self-crosslinked polymer film Sb1 on the PTFE plate is obtained, where the surface density of one side of both porous self-crosslinked polymer films is 0.1 g / m ² and the other side. The thickness of was 0.2 μm.

(3) A _{slurry having a mass ratio of 100: 0.8: 0.5 was prepared from LiCoO 2} , PVDF binder, and carbon black, coated on aluminum foil, and dried to obtain a thickness of 0.114 mm. A LiCoO ₂ positive electrode plate having LiCoO 2 was prepared. The following was also performed in the same manner. Styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) are dissolved in water and stirred with artificial graphite and conductive material at a mass ratio of 2.5: 1.5: 90: 6 at high speed for 3.5 hours at room temperature. Then, the stirred material was coated on the copper foil and dried to prepare a graphite negative electrode plate having a thickness of 0.135 mm. The following was also performed in the same manner.

In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Sa1 were wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D1.

Embodiment 2
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Vinylidene Fluoride-Hexafluoropropylene Copolymer Emulsion (Arkema, name 10278), Self-Crossed Pure Acrylic Emulsion (Shanghai Aigao Chemical Co., Ltd., Name 1005), and Self-Crossed Styrene-Acrylic Emulsion (Shanghai Aigao Chemical Co.) , Ltd., name S601) was mixed at a mass ratio of 12: 4: 4 solid content, an appropriate amount of water was added thereto, and the mixture was uniformly stirred to obtain a total solid content of 5% by weight. The slurry to have was prepared.

(2) The above slurry was screen-printed (at a temperature of 75 ° C.) on the surfaces of both sides of the CCL / PE / CCL (1 μm / 9 μm / 1 μm) base film and on the surface of one side of the PTFE plate, and then By drying at 50 ° C., a CCL / PE / CCL base film (called a ceramic separator Sa2) containing a porous self-crosslinked polymer film Sa2 and a porous self-crosslinked polymer film Sb2 on a PTFE plate were obtained. Here, the surface density of one side of both porous self-crosslinked polymer films was 0.2 g / m ² , and the thickness of one side was 0.4 μm.

(3) In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Sa2 were wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D2.

Embodiment 3
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), vinylidene fluoride-hexafluoropropylene copolymer emulsion (Archema, name 10278), self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Inc.). Ltd., named 1005), and self-crosslinked styrene-acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., named S601) were mixed in a solid content mass ratio of 12: 6: 1: 1 and suitable for this. A volume of water was added and stirred uniformly to prepare a slurry with a total solid content of 10% by weight.

(2) The above slurry was sprayed (at a spray temperature of 58 ° C.) on both surfaces of the PE (9 μm) base film and on the surface of one side of the PTFE plate, and then dried at 50 ° C., respectively. A PE base membrane containing the porous self-crosslinked polymer membrane Sa3 (referred to as battery separator Sa3) and a porous self-crosslinked polymer membrane Sb3 on a PTFE plate were obtained, where one of both porous self-crosslinked polymer membranes. The surface density on the side was 0.3 g / m ² , and the thickness on one side was 0.6 μm.

(3) In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Sa3 were wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D3.

Embodiment 4
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), vinylidene fluoride-hexafluoropropylene copolymer emulsion (Archema, name 10278), and self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Inc.). , Ltd., No. 1005) at a mass ratio of 12.7: 6.3: 1 solid content, add an appropriate amount of water to this, and stir uniformly to 1% by weight of all solids. A slurry having a content was prepared.

(2) The above slurry is screen-printed (at a temperature of 40 ° C.) on the surfaces of both sides of the PE / CCL (9 μm / 2 μm) base film and on the surface of one side of the PTFE plate, and then at 50 ° C. By drying, a PE / CCL base film (referred to as ceramic separator Sa4) containing a porous self-crosslinked polymer film Sa4 and a porous self-crosslinked polymer film Sb4 on a PTFE plate are obtained, where both are porous. The surface density on one side of the quality self-crosslinked polymer coating was 0.1 g / m ² , and the thickness on one side was 0.2 μm.

(3) In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Sa4 are wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which is called D4, and here, CCL. Facing the positive electrode plate.

Embodiment 5
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1005), and self-crosslinked styrene-acrylic emulsion (Shanghai). Aigao Chemical Co., Ltd. (named S601) was mixed at a mass ratio of solid content of 6: 1: 13, to which an appropriate amount of water was added, and the mixture was uniformly stirred to make 5% by weight of all solids. A slurry having a content was prepared.

(2) By spraying the above slurry on the surfaces on both sides of the PE (9 μm) base film and on the surface on one side of the PTFE plate (at a spray temperature of 75 ° C.), and then drying at 50 ° C. , A PE base membrane (referred to as battery separator Sa5) containing the porous self-crosslinked polymer membrane Sa5, respectively, and a porous self-crosslinked polymer membrane Sb5 on a PTFE plate were obtained, wherein both porous self-crosslinked polymer membranes were obtained. The surface density on one side was 0.2 g / m ² , and the thickness on one side was 0.4 μm.

(3) In the drying chamber, a LiCoO ₂ positive electrode plate, a graphite negative electrode plate, and a battery separator Sa5 were wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D5.

Embodiment 6
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), vinylidene fluoride-hexafluoropropylene copolymer emulsion (Archema, name 10278), and self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Inc.). , Ltd., No. 1005) at a mass ratio of 11.4: 7.6: 1 solid content, add an appropriate amount of water to this, and stir uniformly to 10% by weight of all solids. A slurry having a content was prepared.

(2) The slurry is screen-printed (at a temperature of 58 ° C.) on the surfaces of both sides of the CCL (1 μm) base film and on the surface of one side of the PTFE plate, and then dried at 50 ° C. , A CCL base membrane (referred to as battery separator Sa6) containing the porous self-crosslinked polymer membrane Sa6, respectively, and a porous self-crosslinked polymer membrane Sb6 on a PTFE plate, wherein both porous self-crosslinked polymer membranes The surface density on one side was 0.3 g / m ² , and the thickness on one side was 0.6 μm.

(3) In the drying chamber, a LiCoO ₂ positive electrode plate, a graphite negative electrode plate, and a battery separator Sa6 were wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D6.

Embodiment 7
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1040), vinylidene fluoride-hexafluoropropylene copolymer emulsion (Archema, name 10278), and self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Inc.). , Ltd., No. 1005) in a mass ratio of 9.5: 9.5: 1 solid content, add an appropriate amount of water to this, and stir uniformly to 1% by weight of all solids. A slurry having a content was prepared.

(2) By spraying the above slurry on the surfaces on both sides of the PE (9 μm) base film and on the surface on one side of the PTFE plate (at a spray temperature of 40 ° C.), and then drying at 50 ° C. , A PE base membrane (referred to as battery separator Sa7) containing the porous self-crosslinked polymer membrane Sa7, respectively, and a porous self-crosslinked polymer membrane Sb7 on a PTFE plate were obtained, wherein both porous self-crosslinked polymer membranes were obtained. The surface density on one side was 0.1 g / m ² , and the thickness on one side was 0.2 μm.

(3) In the drying chamber, a LiCoO ₂ positive electrode plate, a graphite negative electrode plate, and a battery separator Sa7 were wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D7.

8th Embodiment
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Vinylidene fluoride-hexafluoropropylene copolymer emulsion (Arkema, name 10278) and self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1005) in a mass ratio of 19: 1 solid content. The mixture was mixed, an appropriate amount of water was added thereto, and the mixture was uniformly stirred to prepare a slurry having a total solid content of 5% by weight.

(2) The slurry is screen-printed (at a temperature of 75 ° C.) on the surfaces of both sides of the CCL (1 μm) base film and on the surface of one side of the PTFE plate, and then dried at 50 ° C. , A CCL base membrane (referred to as battery separator Sa8) containing the porous self-crosslinked polymer membrane Sa8, respectively, and a porous self-crosslinked polymer membrane Sb8 on a PTFE plate, wherein both porous self-crosslinked polymer membranes The surface density on one side was 0.2 g / m ² , and the thickness on one side was 0.4 μm.

(3) In the drying chamber, a LiCoO ₂ positive electrode plate, a graphite negative electrode plate, and a battery separator Sa8 were wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D8.

Embodiment 9
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

(1) Vinylidene fluoride-hexafluoropropylene copolymer emulsion (Arkema, name 10278) and self-crosslinked pure acrylic emulsion (Shanghai Aigao Chemical Co., Ltd., name 1005) in a mass ratio of 18: 2 solid content. The mixture was mixed, an appropriate amount of water was added thereto, and the mixture was uniformly stirred to prepare a slurry having a total solid content of 10% by mass.

(2) By spraying the above slurry on the surfaces on both sides of the PE (9 μm) base film and on the surface on one side of the PTFE plate (at a spray temperature of 58 ° C.), and then drying at 50 ° C. A PE base membrane (referred to as battery separator Sa9) containing the porous self-crosslinked polymer membrane Sa9 and a porous self-crosslinked polymer membrane Sb9 on a PTFE plate were obtained, respectively, where one of the two porous self-crosslinked polymer membranes was obtained. The surface density on the side was 0.3 g / m ² , and the thickness on one side was 0.6 μm.

(3) In the drying chamber, a LiCoO ₂ positive electrode plate, a graphite negative electrode plate, and a battery separator Sa9 were wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called D9.

Embodiment 10
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

A battery separator and a lithium ion battery were produced by the method of the first embodiment. The difference is that the slurry forming the bonding layer is an acrylonitrile-acrylate copolymer emulsion (Shanghai Aigao Chemical Co., Ltd., name A1030, 15% by weight polyacrylonitrile segment, 30% by weight butyl polyacrylate segment, 45% by weight. Polymethyl methacrylate segment, 5% by weight ethyl polyacrylate segment, and 5% by weight polyacrylic acid segment were included, the glass transition temperature Tg = 28 ° C., and the solid content was 50% by weight). The weight ratio of the solid content of A1030 to the total solid content of 1040 and 1005 is 1: 1 and the CCL / PE / CCL base film (battery separator) containing the porous self-crosslinked polymer film Sa10. A porous self-crosslinked polymer film Sb10 on a PTFE plate (referred to as Sa10), and a lithium ion battery (referred to as D10) are obtained, where the surface density on one side of both porous self-crosslinked polymer films is determined. It was 0.1 g / m ² and the thickness on one side was 0.2 μm.

Embodiment 11
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

A battery separator and a lithium ion battery were produced by the method of the first embodiment. The difference is that the slurry forming the bonding layer further contains a chloroprene-acrylonitrile emulsion (Shanghai Aigao Chemical Co., Ltd., name C056, glass transition temperature Tg = 10 ° C., solid content was 45% by weight). That is, the weight ratio of the solid content of C056 to the total solid content of 1040 and 1005 is 3: 1 and the CCL / PE / CCL base film (battery separator Sa11) containing the porous self-crosslinked polymer film Sa11. , A porous self-crosslinked polymer film Sb11 on a PTFE plate, and a lithium ion battery (referred to as D11), where the surface density on one side of both porous self-crosslinked polymer films is 0. It was .1 g / m ² and the thickness on one side was 0.2 μm.

Embodiment 12
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

A battery separator and a lithium ion battery were produced by the method of the first embodiment. The difference is that the slurry forming the bonding layer further contained styrene-butadiene latex (Japan Zeon Co., Ltd., name 9074, glass transition temperature Tg = -61 ° C., solid content was 50% by weight). That is, the weight ratio of the solid content of 9074 to the total solid content of 1040 and 1005 is 1: 1 and the CCL / PE / CCL base film containing the porous self-crosslinked polymer film Sa12 (with the battery separator Sa12). ), The porous self-crosslinked polymer film Sb12 on the PTFE plate, and the lithium ion battery (referred to as D12) are obtained, where the surface density on one side of both porous self-crosslinked polymer films is 0. It was 1 g / m ² and the thickness on one side was 0.2 μm.

Embodiment 13
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

A battery separator and a lithium ion battery were produced by the method of the fourth embodiment. The difference is that instead of vinylidene fluoride-hexafluoropropylene copolymer emulsion, vinylidene fluoride-hexafluoropropylene copolymer powder with the same solid content (glass transition temperature was -55 ° C., Archema, name Kynar powerflex LBG) ) Was used. The specific method for preparing this dispersed liquid is as follows:
(1) PVA having a weight average molecular weight of 95,000 g / mol was dissolved in water at 100 ° C. to form a 2.5% by weight aqueous solution of PVA.

(2) PAA having a weight average molecular weight of 9000 g / mol and a 10 wt% NaOH solution were mixed with water to form a 5 wt% aqueous solution of PAANA.

(3) The above-mentioned aqueous solution of PVA, aqueous solution of PAANA, and water are mixed under mechanical stirring at a rotation speed of 30 Hz so that the concentrations of PVA and PAANA in water are 0.05% by weight, respectively, and are uniform. After mixing with, an aqueous solution of a dual dispersant of PVA and PAANA was formed. The mass percent value of the dispersant PVA with respect to LBG is 0.4% by weight, and the mass percent value of the dispersant PAANA with respect to LBG is 0.4% by weight, so that the solid content of LBG is 12.5% by weight. Kynar powerflex LBG was slowly added to a sufficient amount of aqueous solution of the dual dispersant of PVA and PAANA under mechanical stirring at a rotation rate of 30 Hz. After completion of the addition, the mixture was first stirred at a high speed of 50 Hz for 1 hour and then homogenized 5 times with a homogenizer under a pressure of 80 MPa to form a dispersed liquid of LBG.

The resulting slurry is printed by the method of Embodiment 4 on both sides of the PE / CCL (9 μm / 2 μm) base film and on the surface of one side of the PTFE plate and then dried at 50 ° C. A PE / CCL base membrane (referred to as battery separator Sa13) containing the porous self-crosslinked polymer membrane Sa13 and a porous self-crosslinked polymer membrane Sb13 on a PTFE plate were obtained, respectively, and both porous self-crosslinked membranes were obtained here. The surface density on one side of the polymer film was 0.1 g / m ² , and the thickness on one side was 0.2 μm.

The method of the fourth embodiment was carried out on the obtained battery separator to prepare a lithium ion battery separator, which was called D13.

Embodiment 14
The present embodiment is for explaining the battery separator and the lithium ion battery provided by the present disclosure, and a method for manufacturing the same.

A battery separator and a lithium ion battery were produced by the method of the second embodiment. The difference was that the same weight portion of the self-crosslinked pure acrylic emulsion 1020 was used instead of the self-crosslinked pure acrylic emulsion 1005.

The resulting slurry was printed by the method of Embodiment 2 on both sides of the CCL / PE / CCL (1 μm / 9 μm / 1 μm) base film and on the surface of one side of the PTFE plate, then at 50 ° C. By drying with, a CCL / PE / CCL base film (referred to as battery separator Sa14) containing the porous self-crosslinked polymer film Sa14 and a porous self-crosslinked polymer film Sb14 on a PTFE plate were obtained, respectively. The surface density of one side of both porous self-crosslinked polymer films was 0.2 g / m ² , and the thickness of one side was 0.4 μm.

The method of the second embodiment was carried out on the obtained battery separator to prepare a lithium ion battery separator, which was called D14.

Comparative Embodiment 1
This comparative embodiment is for explaining a battery separator and a lithium ion battery as a reference, and a method for manufacturing the same.

A slurry and a bonding layer were prepared by the method of the fourth embodiment. The difference is that the bonding layer was formed by knife coating, a PE / CCL base film containing a dense self-crosslinking polymer film Ra1 (called a battery separator Ra1), and a dense self-crosslinking on a PTFE plate. Polymer films Rb1 were obtained, respectively, where the surface density on one side of both dense self-crosslinked polymer films was 1 g / m ² and the thickness on one side was 2 μm.

(3) In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Ra1 were wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called DD1.

Comparative Embodiment 2
This comparative embodiment is for explaining a battery separator and a lithium ion battery as a reference, and a method for manufacturing the same.

A slurry and a bonding layer were prepared by the method of the first embodiment. The difference is that the bonding layer was formed by knife coating, a CCL / PE / CCL base film containing a dense self-crosslinked polymer film Ra2 (called a battery separator Ra2), and a dense PTFE plate. A self-crosslinked polymer film Rb2 was obtained, respectively, where the surface density on one side of both dense self-crosslinked polymer films was 1.5 g / m ² and the thickness on one side was 3 μm. rice field.

(3) In the drying chamber, the LiCoO ₂ positive electrode plate, the graphite negative electrode plate, and the battery separator Ra2 were wound to prepare SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which was called DD2.

Comparative Embodiment 3
This comparative embodiment is for explaining a battery separator and a lithium ion battery as a reference, and a method for manufacturing the same.

In the drying chamber, a LiCoO ₂ positive electrode plate, a lead negative electrode plate, and a PE / CCL (9 μm / 2 μm) separator are wound to prepare an SL435573 LiCoO ₂ / graphite pouch type polymer lithium ion battery, which is called DD3. The CCL faces the positive electrode plate.

Test Example (1) Observation of surface topography:
Microtopography of the CCL surfaces of the porous self-crosslinked polymer films Sa1 and Sa4 obtained in Embodiments 1 and 4 and the PE surface of Sa4 was observed with a scanning electron microscope (SEM, JEOL, JSM-7600FE). , The results are shown in FIGS. 1 (a), 1 (b), and 1 (c), respectively. As can be seen from FIG. 1 (a), a self-crosslinked polymer film (bonding layer, the same applies hereinafter) having excellent porosity can be formed by spraying on the surface of the CCL base film. As can be seen from FIG. 1 (b), the self-crosslinked polymer film having excellent porosity can also be formed by screen printing on the surface of the base film CCL. As can be seen from FIG. 1 (c), the self-crosslinked polymer film having excellent porosity can also be formed by screen printing on the surface of the base film PE, and the self-crosslinked polymer is mostly spherical.

(2) Porosity test:
The porous self-crosslinked polymer membranes Sb1 to Sb14 obtained in Examples 1 to 14 were cut into disks having a diameter of 17 mm, the thickness was measured, the disks were weighed, and immersed in n-butanol for 2 hours. Then, it was taken out, the liquid on the surface of the film was sucked up with a filter paper, and the mass of the film at this point was weighed. The following formula:

P is the porosity, M ₀ is the mass (g) of the dry film, M is the mass (g) after immersion in n-butanol for 2 hours, and ρ _BuOH is n-butanol. Density (g / cm ³ ), r is the radius of the film (cm), and d is the thickness of the film (cm). The results of the porosity test are shown in Table 1. As can be seen from the results in Table 1, the porosity of the porous self-crosslinked polymer membrane is higher.

(3) Liquid absorption rate test:
The porous self-crosslinked polymer films Sb1 to Sb14 obtained in Examples 1 to 14 were cut into a disk having a diameter of 17 mm, dried, weighed, and then an electrolyte (this electrolyte was 32.5% by weight EC (). Ethylene carbonate), 32.5% by weight EMC (ethylmethyl carbonate), 32.5% by weight DMC (dimethyl carbonate), 2.5% by weight VC (vinylene carbonate), and 1 mol / L LiPF ₆ (hexa). It was immersed in (containing lithium fluorophosphate) for 24 hours, then removed, and the liquid on the surface of the film was sucked up with a filter paper, and the weight of the film at this point was weighed. All work was done in a glove box filled with argon. Then the following formula:

Liquid absorption rate% = (Wi-W) / W x 100%

The liquid absorption rate was calculated by

Here, W is the mass (g) of the dry membrane, and Wi is the mass (g) of the dry membrane after being immersed in the electrolyte for 24 hours. The results of the liquid absorption rate test are shown in Table 1. As can be seen from the results in Table 1, the liquid absorption rate of the porous self-crosslinked polymer film is much higher than the liquid absorption rate of the dense self-crosslinked polymer film.

(4) Test of ionic conductivity of gel polymer electrolyte:
The porous self-crosslinked polymer films Sb1 to Sb14 obtained in Examples 1 to 14 and the dense self-crosslinked polymer films Rb1 and Rb2 obtained in Comparative Examples 1 and 2 were cut into a disk having a diameter of 17 mm and dried. Sufficient amount of electrolyte placed between two stainless steel (SS) electrodes (this electrolyte is 32.5% by weight EC (ethylene carbonate), 32.5% by weight EMC (ethyl methyl carbonate). (Contains 32.5% by weight DMC (dimethyl carbonate), 2.5% by weight VC (vinylene carbonate) and 1 mol / L LiPF ₆ (lithium hexafluorophosphate)) for AC impedance experiments. It was enclosed in the 2016 button cell of. The intersection of the straight line and the real axis is the bulk resistance of the electrolyte, from which the ionic conductivity can be determined: σ = L / A · R (in the formula, L is the thickness of the membrane (cm). ^{A is the contact area (cm 2} ) between the stainless steel plate and the membrane, and R is the bulk resistance (mS) of the electrolyte). The results of conductivity are shown in Table 1. As can be seen from the results in Table 1, the bulk impedance of the porous self-crosslinked GPE is much lower than the bulk impedance of the dense self-crosslinked GPE, and the ionic conductivity is significantly increased.

(5) Test of adhesion of film to positive electrode and negative electrode:
The completed battery obtained in the first embodiment (hot-pressed at 85 ° C. under a pressure of 1 MPa for 4 hours) was cut in a fully charged state, and photographs of the obtained positive electrode plate, negative electrode plate and separator were taken. The results are shown in FIG. As can be seen from FIG. 2, all the black positive electrode materials are adhered to the porous self-crosslinked separator, and a part of the negative electrode material is adhered to the porous self-crosslinked separator. It can be seen that the porous self-crosslinked polymer film obtained by the present disclosure is widely adhered to the positive and negative electrodes of the lithium ion battery, and thus the hardness of the pouch cell is significantly increased.

(6) Battery rate performance test:
Using a lithium-ion battery performance test cabinet (Guangzhou Lanqi, BK6016), the rate discharge performance test of the stepwise polymer lithium-ion batteries obtained in Embodiments 1 to 14 and Comparative Embodiments 1 to 3 was performed. The rate discharge test method is as follows: Charge the battery to 4.35V with 0.5C (1C = 2520mA) constant current and constant voltage, shut off at 0.02C, leave for 5 minutes, 0.2C / The discharge capacity was recorded by discharging to 3.0 V at 0.5C / 1C / 2C / 3C / 4C. The results of the rate discharge test are shown in Table 2. The test results show that the high-rate discharge performance of the lithium-ion battery of the porous self-crosslinked GPE is much higher than that of the lithium-ion battery of the dense self-crosslinked GPE. This is because the increase in conductivity may reduce the polarization phenomenon of the charge-discharge process, which is beneficial for the movement of lithium ions.

(7) Room temperature cycle performance test:
By using a lithium ion battery performance test cabinet (Guangzhou Lanqi, BK6016), a 25 ° C. cycle performance test of the stepwise polymer lithium ion battery obtained in the first embodiment and the second embodiment was performed. The test method is as follows: The battery was charged at 1C to 4.35V, shut off at 0.1C, left for 10 minutes, discharged at 1C to 3.0V, and this cycle was repeated. The result of the cycle is shown in FIG. The test results show that the cycle performance of the lithium ion battery of the porous self-crosslinked gel polymer electrolyte produced according to the present disclosure is much superior to that of the battery using the dense self-crosslinked polymer electrolyte. Lithium ions move slowly in the dense self-crosslinking polymer electrolyte, so batteries with dense self-crosslinking polymer electrolytes undergo large polarization during charging and discharging, and lithium dendrites during each cycle of charging steps. Is produced and lithium is consumed, resulting in a faster volume loss. However, batteries using porous self-crosslinked gel polymer electrolytes do not exhibit these drawbacks, thus greatly improving cycle performance.

(8) High temperature cycle performance test:
By using a lithium ion battery performance test cabinet (Guangzhou Lanqi, BK6016), a 45 ° C. cycle performance test of the stepwise polymer lithium ion battery obtained in the first embodiment and the third embodiment was performed. The test method is as follows: The battery was charged at 1C to 4.35V, shut off at 0.1C, left for 10 minutes, discharged at 1C to 3.0V, and this cycle was repeated. The result of the cycle is shown in FIG. The test results show that the high temperature cycle performance of the lithium ion battery of the porous self-crosslinked gel polymer electrolyte produced according to the present disclosure is better than that of the ceramic separator battery. The porous self-crosslinked polymer membrane produced according to the present disclosure is beneficial for improving the high temperature performance of a battery when used in a battery.

(9) High temperature storage performance test:
The lithium ion batteries obtained in the first embodiment and the third embodiment were subjected to a storage performance test at 85 ° C. for 4 hours. The test method is as follows: 1. By using a lithium-ion battery performance test cabinet (Guangzhou Lanqi, BK6016), the battery is charged to 4.35V at 0.5C, shut off at 0.02C, the battery is left for 5 minutes, 3 at 0.2C. Discharge to .0 V and record pre-discharge capacity; 2. The battery was charged to 4.35V at 0.5C, shut off at 0.02C, the battery was left for 1 hour and tested for previous voltage, internal resistance, and thickness; Batteries were placed in an oven at 85 ° C. and stored for 4 hours; 4. Immediately after storage, the thickness was tested and the batteries were left at room temperature for 2 hours to test for cooled thickness, later voltage, and later internal resistance; The battery was discharged to 3.0 V at 0.2 C, the surplus capacity was recorded, and the capacity surplus ratio (surplus capacity divided by the preliminary discharge capacity) was calculated; 6. The battery was fully charged at 0.5C, left for 5 minutes, discharged to 3.0V at 0.2C, the recovery capacity was recorded, and the capacity recovery rate (recovery capacity divided by the previous capacity) was calculated. The test results are shown in Table 3. As can be seen from Table 3, the porous gel polymer lithium-ion battery produced by the present disclosure has a higher capacity surplus rate, capacity recovery rate, voltage change rate, and thickness change rate after high-temperature storage than the ceramic separator battery. Much better. Therefore, the porous self-crosslinked polymer membrane provided by the present disclosure will be beneficial in improving the high temperature performance of the battery when used in the battery.

Although the implementation form of the present disclosure has been described in detail above, the present disclosure is not limited to the specific details of the above-mentioned implementation form, and the technical solution of the present disclosure is within the scope of the technical concept of the present disclosure. Various simple variants of the scheme can be made. All of these simple variants fall within the protection of this disclosure.

It should be further noted that the particular technical features described in the particular implementations described above can be combined in any suitable manner if there is no conflict. To avoid unnecessary repetition, the various possible combinations are not further described in this disclosure.

Moreover, any combination of the various implementations of the present disclosure is possible without departing from the concept of the present disclosure, which should also be considered the content of the present disclosure.

Claims (20)

Porous base membrane and
A battery separator comprising a bonding layer adhered to the surface of at least one side of the porous base membrane.
The bonding layer contains an acrylate crosslinked polymer and contains.
The bonding layer further comprises a styrene-acrylate crosslinked copolymer and / or a vinylidene fluoride-hexafluoropropylene copolymer.
The porosity of the bonding layer is 40 to 65%.
The surface density on one side of the bonding layer is 0.05 to 0.9 mg / cm ² , and the thickness on one side of the bonding layer is 0.1 to 1 μm.
Battery separator. The glass transition temperature of the acrylate crosslinked polymer is −20 ° C. to 60 ° C.
The glass transition temperature of the styrene-acrylate crosslinked copolymer is −30 ° C. to 50 ° C., and
The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is −65 ° C. to −40 ° C.
The battery separator according to claim 1. The bonding layer contains the acrylate-crosslinked polymer and the styrene-acrylate-crosslinked copolymer, but does not contain the vinylidene fluoride-hexafluoropropylene copolymer, and the weight ratio of the acrylate-crosslinked polymer to the styrene-acrylate-crosslinked copolymer is , 1: 0.05 to 1: 2, or the bonding layer contains the acrylate-crosslinked polymer and the vinylidene-hexafluoropropylene copolymer, but does not contain the styrene-acrylate-crosslinked copolymer and. The weight ratio of the acrylate-crosslinked polymer to the vinylidene-hexafluoropropylene copolymer is 1: 0.3 to 1:25, or the bonding layer is the acrylate-crosslinked polymer, the styrene-acrylate-crosslinked copolymer, The weight ratio of the vinylidene fluoride-hexafluoropropylene copolymer and the acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (0.01 to 2). : (0.3-5),
The battery separator according to claim 1. The acrylate crosslinked polymer is
A mixture of a first acrylate-crosslinked polymer, a second acrylate-crosslinked polymer, and / or a third acrylate-crosslinked polymer,
The second acrylate crosslinked polymer, or
Contains the third acrylate crosslinked polymer
The first acrylate crosslinked polymer contains 70-80% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, 10 to 20% by weight of butylpolyacrylate segment, and 2 to 10% by weight. The second acrylate crosslinked polymer comprises 30-40% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, 50-60% by weight of polyacrylic. The third acrylate-crosslinked polymer contains a butyl acid acid segment and a polyacrylic acid segment of 2 to 10% by weight, and the third acrylate crosslinked polymer contains a polymethyl methacrylate segment of 50 to 80% by weight and a polyacrylic acid of 2 to 10% by weight. Contains 15-40% by weight butyl polyacrylate segment and 2-10% by weight polyacrylic acid segment.
The glass transition temperature of the first acrylate crosslinked polymer is 50 ° C to 60 ° C, the glass transition temperature of the second acrylate crosslinked polymer is −20 ° C to −5 ° C, and the third acrylate The glass transition temperature of the crosslinked polymer is 30 ° C to 50 ° C.
The battery separator according to claim 1. The styrene-acrylate crosslinked copolymer is 40 to 50% by weight polystyrene segment, 5 to 15% by weight polymethyl methacrylate segment, 2 to 10% by weight ethyl polyacrylate segment, 30 to 40% by weight polyacrylic acid. The styrene-acrylate crosslinked copolymer contains a butyl segment and a polyacrylic acid segment of 2 to 10% by weight, and the glass transition temperature of the styrene-acrylate crosslinked copolymer is 15 ° C to 30 ° C.
The battery separator according to claim 1. The vinylidene fluoride-hexafluoropropylene copolymer contains 80 to 98% by weight of polyvinylidene fluoride segment and 2 to 20% by weight of polyhexafluoropropylene segment, and the glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is , -60 ° C to -40 ° C,
The battery separator according to claim 1. The bonding layer contains the first acrylate crosslinked polymer, the second acrylate crosslinked polymer, and the styrene-acrylate crosslinked copolymer, but does not contain the vinylidene fluoride-hexafluoropropylene copolymer, and the first acrylate. The weight ratio of the crosslinked polymer to the second acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer is (5-10): 1: (10 to 13), or the bonding layer is the first acrylate. The first acrylate-crosslinked polymer vs. the second acrylate-crosslinked polymer, including the crosslinked polymer, the second acrylate crosslinked polymer, and the vinylidene fluoride-hexafluoropropylene copolymer, but not the styrene-acrylate crosslinked copolymer. The weight ratio of the vinylidene fluoride-hexafluoropropylene copolymer to the vinylidene fluoride is (5 to 15): 1: (5 to 12), or the bonding layer is the second acrylate crosslinked polymer and the vinylidene fluoride. The weight ratio of the second acrylate-crosslinked polymer to the vinylidene fluoride-hexafluoropropylene copolymer, including the-hexafluoropropylene copolymer but not the styrene-acrylate crosslinked polymer, is 1: 5 to 1:20. Alternatively, the bonding layer comprises the second acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer, and the vinylidene fluoride-hexafluoropropylene copolymer, and the second acrylate crosslinked polymer versus the styrene-acrylate crosslinked copolymer. The weight ratio of the vinylidene fluoride-hexafluoropropylene copolymer to the fluoropropylene copolymer is 1: (0.5 to 2) :( 1 to 5), or the bonding layer is the third acrylate crosslinked polymer, the styrene. The weight ratio of the third acrylate crosslinked polymer to the styrene-acrylate crosslinked polymer to the vinylidene fluoride-hexafluoropropylene copolymer comprising the vinylidene fluoride-hexafluoropropylene copolymer is 1: ( 0.5-2): (1-5), or the bonding layer is said to be the first acrylate crosslinked polymer, the second acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer, and the vinylidene fluoride. -Contains hexafluoropropylene polymer, said The weight ratio of the first acrylate crosslinked polymer to the second acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is (10 to 15): 1: (0.5 to 2). ): (5 to 10),
The first acrylate crosslinked polymer contains 70-80% by weight of polymethyl methacrylate segment, 2-10% by weight of ethyl polyacrylate segment, 10 to 20% by weight of butyl polyacrylate segment, and 2 to 10% by weight. The second acrylate crosslinked polymer comprises 30-40% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, 50-60% by weight of polyacrylic acid. The third acrylate crosslinked polymer comprises a butyl acid acid segment and a polyacrylic acid segment of 2 to 10% by weight, and the third acrylate crosslinked polymer is a methyl methacrylate segment of 50 to 80% by weight and an ethyl polyacrylate segment of 2 to 10% by weight. The styrene-acrylate crosslinked polymer comprises 15-40% by weight butyl polyacrylate segment and 2-10% by weight polyacrylic acid segment, and the styrene-acrylate crosslinked polymer is 40-50% by weight polystyrene segment, 5-15% by weight. Contains 2-10% by weight ethyl polyacrylate segment, 30-40% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment, and said vinylidene fluoride. The hexafluoropropylene copolymer contains 80 to 98% by weight of vinylidene fluoride segment and 2 to 20% by weight of polyhexafluoropropylene segment, and the glass transition temperature of the first acrylate crosslinked polymer is 50 ° C. to 60 ° C. The glass transition temperature of the second acrylate crosslinked polymer is −20 ° C. to −5 ° C., and the glass transition temperature of the third acrylate crosslinked polymer is 30 ° C. to 50 ° C. The glass transition temperature of the styrene-acrylate crosslinked copolymer is 15 ° C. to 30 ° C., and the glass transition temperature of the vinylidene fluoride-hexafluoropropylene polymer is −60 ° C. to −40 ° C.
The battery separator according to claim 4. The bonding layer further comprises at least one of an acrylonitrile-acrylate copolymer, a chloroprene-acrylonitrile copolymer, and a styrene-butadiene copolymer.
When the bonding layer further contains the acrylonitrile-acrylate copolymer, the weight ratio of the acrylonitrile-acrylate copolymer to the acrylate crosslinked polymer is 0.05: 1 to 2: 1.
When the bonding layer further comprises the chloroprene-acrylonitrile copolymer, the weight ratio of the chloroprene-acrylonitrile copolymer to the acrylate crosslinked polymer is 0.15: 1 to 7: 1, and the bonding layer is the styrene-butadiene. When further copolymers are included, the weight ratio of the styrene-butadiene copolymer to the acrylate crosslinked polymer is 0.05: 1-2: 1.
The battery separator according to any one of claims 1 to 6. The porous base film is a polymer-based film or a ceramic-based film, and the ceramic-based film comprises a polymer-based film and a ceramic layer arranged on the surface of at least one side of the polymer-based film. Including, the overall thickness of the porous base membrane is 9-22 μm.
The battery separator according to any one of claims 1 to 6. A step of adhering a slurry containing a self-crosslinked pure acrylic emulsion and a self-crosslinked styrene-acrylic emulsion and / or a vinylidene fluoride-hexafluoropropylene copolymer emulsion to the surface of at least one side of the porous base film.
It then comprises the step of drying to form a bonding layer having a porosity of 40-65% on the surface of at least one side of the porous base film.
The porosity of the bonding layer is 40 to 65%.
The surface density on one side of the bonding layer is 0.05 to 0.9 mg / cm ² , and the thickness on one side of the bonding layer is 0.1 to 1 μm.
Manufacturing method of battery separator. The glass transition temperature of the acrylate-crosslinked polymer in the self-crosslinked pure acrylic emulsion is −20 ° C. to 60 ° C., and the glass transition temperature of the styrene-acrylate-crosslinked copolymer in the self-crosslinked styrene-acrylic emulsion is −30 ° C. to −30 ° C. The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer in the vinylidene fluoride-hexafluoropropylene copolymer emulsion is −65 ° C. to −40 ° C., which is 50 ° C.
The method according to claim 10. The slurry contains the self-crosslinked pure acrylic emulsion and the self-crosslinked styrene-acrylic emulsion, but does not contain the vinylidene fluoride-hexafluoropropylene copolymer emulsion, the self-crosslinked pure acrylic emulsion vs. the self-crosslinked styrene-acrylic emulsion. The weight ratio of the solid content of is 1: 0.05 to 1: 2, or the slurry comprises the self-crosslinked pure acrylic emulsion and the vinylidene fluoride-hexafluoropropylene copolymer emulsion, but said self. The weight ratio of the solid content of the self-crosslinked pure acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion, which does not contain the crosslinked styrene-acrylic emulsion, is 1: 0.3 to 1:25 or said. The slurry comprises the self-crosslinked pure acrylic emulsion, the self-crosslinked styrene-acrylic emulsion, and the vinylidene fluoride-hexafluoropropylene copolymer emulsion, the self-crosslinked pure acrylic emulsion vs. the self-crosslinked styrene-acrylic emulsion vs. the fluoride. The weight ratio of the solid content of the vinylidene-hexafluoropropylene copolymer emulsion is 1: (0.01-2) :( 0.3-5).
The method according to claim 10. The self-crosslinked pure acrylic emulsion
A mixture of a first self-crosslinked pure acrylic emulsion, a second self-crosslinked pure acrylic emulsion, and / or a third self-crosslinked pure acrylic emulsion.
The second self-crosslinked pure acrylic emulsion, or
The third self-crosslinked pure acrylic emulsion.
The acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion is 70 to 80% by weight of polymethyl methacrylate segment, 2 to 10% by weight of ethyl acrylate segment, and 10 to 20% by weight of butyl polyacrylate. Contains segments and 2-10 wt% polyacrylic acid segments
The acrylate-crosslinked polymer in the second self-crosslinked pure acrylic emulsion contains 30-40% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, and 50-60% by weight of butyl polyacrylate. Contains segments and 2-10 wt% polyacrylic acid segments and
The acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion is 50 to 80% by weight of polymethyl methacrylate segment, 2 to 10% by weight of ethyl polyacrylate segment, and 15 to 40% by weight of butyl polyacrylate. Contains segments and 2-10 wt% polyacrylic acid segments
The glass transition temperature of the acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion is 50 ° C. to 60 ° C., and the glass transition temperature of the acrylate-crosslinked polymer in the second self-crosslinked pure acrylic emulsion is The glass transition temperature of the acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion is −20 ° C. to −5 ° C., and is 30 ° C. to 50 ° C.
The method according to claim 10. The styrene-acrylate crosslinked copolymer in the self-crosslinked styrene-acrylic emulsion is 40-50% by weight polystyrene segment, 5-15% by weight polymethylmethacrylate segment, 2-10% by weight ethyl polyacrylate segment, 30. Includes ~ 40% by weight butyl polyacrylate segment and 2-10% by weight polyacrylic acid segment.
The glass transition temperature of the styrene-acrylate crosslinked copolymer is 15 ° C to 30 ° C.
The method according to claim 10. The vinylidene fluoride-hexafluoropropylene copolymer in the vinylidene fluoride-hexafluoropropylene copolymer emulsion contains 80-98% by weight of polyvinylidene fluoride segment and 2-20% by weight of polyhexafluoropropylene segment.
The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer is −60 ° C. to −40 ° C.
The method according to claim 10. The slurry comprises the first self-crosslinked pure acrylic emulsion, the second self-crosslinked pure acrylic emulsion, and the self-crosslinked styrene-acrylic emulsion, but not the vinylidene fluoride-hexafluoropropylene copolymer emulsion. The weight ratio of the solid content of the first self-crosslinked pure acrylic emulsion to the second self-crosslinked pure acrylic emulsion to the self-crosslinked styrene-acrylic emulsion is (5 to 10): 1: (10 to 13). The slurry, or the slurry, comprises said first self-crosslinked pure acrylic emulsion, said second self-crosslinked pure acrylic emulsion, and said vinylidene fluoride-hexafluoropropylene copolymer emulsion, but said said self-crosslinked styrene-acrylic emulsion. The weight ratio of the solid content of the first self-crosslinked pure acrylic emulsion to the second self-crosslinked pure acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion is (5 to 15): 1. : (5-12), or the slurry comprises the second self-crosslinked pure acrylic emulsion and the vinylidene fluoride-hexafluoropropylene copolymer emulsion but not the self-crosslinked styrene-acrylic emulsion. The weight ratio of the solid content of the second self-crosslinked pure acrylic emulsion to the vinylidene fluoride-hexafluoropropylene copolymer emulsion is 1: 5 to 1:20, or the slurry is the second self. The second self-crosslinked pure acrylic emulsion vs. the self-crosslinked styrene-acrylic emulsion vs. the vinylidene fluoride-containing the crosslinked pure acrylic emulsion, the self-crosslinked styrene-acrylic emulsion, and the vinylidene fluoride-hexafluoropropylene copolymer emulsion. The weight ratio of the solid content of the hexafluoropropylene copolymer emulsion is 1: (0.5-2): (1-5), or the slurry is a third self-crosslinked pure acrylic emulsion, said self-crosslinked. The third self-crosslinked pure acrylic emulsion vs. the self-crosslinked styrene-acrylic emulsion vs. the vinylidene fluoride-hexafluoropropylene copolymer emulsion comprising the styrene-acrylic emulsion and the vinylidene fluoride-hexafluoropropylene copolymer emulsion. The weight ratio of the solid content of is 1: (0.5 to 2): (1 to 5), or the slurry is the first self-crosslinked pure acrylic emulsion, the second self-crosslinked pure. Acrylic emulsion, said self-crosslinked styrene-acrylic emulsion, and said vinylidene fluoride-hexafluoropropylene copolymer emulsion, said first self-crosslinked pure acrylic emulsion vs. said second self-crosslinked pure acrylic emulsion vs. said self-crosslinked styrene-. The weight ratio of the solid content of the vinylidene fluoride-hexafluoropropylene copolymer emulsion to the acrylic emulsion is (10 to 15): 1: (0.5 to 2) :( 5 to 10).
The acrylate-crosslinked polymer in the first self-crosslinked pure acrylic emulsion contains 70-80% by weight of polymethylmethacrylate segment, 2-10% by weight of ethylpolyacrylate segment, and 10-20% by weight of polyacrylic acid. The acrylate-crosslinked polymer in the second self-crosslinked pure acrylic emulsion, comprising a butyl segment and 2-10% by weight polyacrylic acid segment, is 30-40% by weight of polymethylmethacrylate segment, 2-10% by weight. The acrylate-crosslinked polymer in the third self-crosslinked pure acrylic emulsion comprises a% ethyl polyacrylate segment, 50-60% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment. , 50-80% by weight polymethyl methacrylate segment, 2-10% by weight ethyl polyacrylate segment, 15-40% by weight butyl polyacrylate segment, and 2-10% by weight polyacrylic acid segment. The styrene-acrylate crosslinked copolymer in the self-crosslinked styrene-acrylic emulsion comprises 40-50% by weight polystyrene segment, 5-15% by weight polymethylmethacrylate segment, 2-10% by weight ethylpolyacrylate segment. 30-40% by weight of polyacrylic acid butyl segment, and include a polyacrylic acid segments 2-10 wt%, and the vinylidene fluoride - hexafluoropropylene copolymer vinylidene fluoride polymer in the emulsion - hexafluoropropylene copolymer, 80 98 wt% of the saw including a polyhexafluoropropylene segment of polyvinylidene fluoride segment and 2-20 wt%, or one the vinylidene fluoride - glass transition temperature of hexafluoropropylene copolymers, at -60 ℃ ~-40 ℃ be,
The method according to any one of claims 13. The slurry further comprises at least one of an acrylonitrile-acrylate copolymer emulsion, a chloroprene-acrylonitrile emulsion, and a styrene-butadiene latex.
When the slurry further comprises the acrylonitrile-acrylate copolymer emulsion, the weight ratio of the solid content of the acrylonitrile-acrylate copolymer emulsion to the self-crosslinked pure acrylic emulsion is 0.05: 1-2: 1.
When the slurry further comprises the chloroprene-acrylonitrile emulsion, the weight ratio of the solid content of the chloroprene-acrylonitrile emulsion to the self-crosslinked pure acrylic emulsion is 0.15: 1-7: 1 and the slurry is When the styrene-butadiene latex is further contained, the weight ratio of the solid content of the styrene-butadiene latex to the self-crosslinked pure acrylic emulsion is 0.05: 1 to 2: 1.
The method according to any one of claims 10 to 15. The bonding method is a spraying method and / or a screen printing method, and the operating temperatures of the spraying method and the screen printing method are independently 30 ° C. to 80 ° C., and the drying temperature is 30 ° C. to 80 ° C. Is,
The method according to any one of claims 10 to 15. A lithium ion battery including a positive electrode plate, a negative electrode plate, an electrolyte, and a battery separator, wherein the battery separator is the battery separator according to any one of claims 1 to 9.
Lithium-ion battery. A step of sequentially laminating or winding a positive electrode plate, a battery separator, and a negative electrode plate to form a rod-shaped core,
Next, the step of injecting the electrolyte into the rod-shaped core and
Including the sealing step
The battery separator is the battery separator according to any one of claims 1 to 9.
A method for manufacturing a lithium-ion battery.

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